Most Earth-like Planets Are Too Radioactive To Live In

The planet Kepler-438b is shown here in front of its violent parent star. Credit: Mark A Garlick/University of Warwick

Kepler-438b, an Earth-size exoplanet is virtually uninhabitable due to superflares emitting from its star

Most Earth-like planets are too radioactive that they are unfit for human habitation, a new research led by University of Warwick suggests.

Kepler-438b is an almost Earth-size exoplanet, which was unveiled back in January and seemed like a promising find. It is right in its star’s habitable zone which made it warm enough to hold liquid water. In fact, it’s the most Earth-like exoplanet discovered to date.

But researchers have found that Kepler-438b is virtually impossible to live in. Superflares emitting from its Red Dwarf star are destroying the atmosphere of the exoplanet and making it uninhabitable.

The superflares take place after every few hundred days and are 10 times more powerful than those explosions that are ever observed in Sun or you can say they are equal to the energy of 100 billion megatons of TNT.

The superflare alone cannot harm that much. It is likely that these flares are associated with a dangerous phenomenon, known as Coronal Mass Ejection (CME), which exerts damaging effects on the habitability of the planet. Kepler-438b is orbiting too close to its star than the Earth is to the Sun.

"If the planet, Kepler-438b, has a magnetic field like the Earth, it may be shielded from some of the effects,” said lead researcher Dr David Armstrong.

“However, if it does not or the flares are strong enough, it could have lost its atmosphere, be irradiated by extra dangerous radiation and be a much harsher place for life to exist.”

Researcher Chloe Pugh from University of Warwick's Centre for Fusion, Space and Astrophysics explains how devastating impact CME can create on atmosphere.

“Coronal Mass Ejections are where a huge amount of plasma is hurled outwards from the Sun, and there is no reason why they should not occur on other active stars as well. The likelihood of a coronal mass ejection occurring increases with the occurrence of powerful flares, and large coronal mass ejections have the potential to strip away any atmosphere that a close-in like planet Kepler-438b might have, rendering it uninhabitable. With little atmosphere, the planet would also be subject to harsh UV and X-ray radiation from the superflares, along with charged particle radiation, all of which are damaging to life.”